Horton

Re: WIP: [[Parallel] Shared] Hash

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Peter Geoghegan <pg@bowt.ie>, Rafia Sabih <rafia.sabih@enterprisedb.com>, Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>, Haribabu Kommi <kommi.haribabu@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>, Robert Haas <robertmhaas@gmail.com>
Date: 2017-03-31T18:35:16Z
Lists: pgsql-hackers 
Hi Thomas,

On 2017-03-31 17:53:12 +1300, Thomas Munro wrote:
> Thanks very much to Rafia for testing, and to Andres for his copious
> review feedback.  Here's a new version.  Changes:

I've not looked at that aspect, but one thing I think would be good is
to first add patch that increases coverage of nodeHash[join].c to nearly
100%.  There's currently significant bits of nodeHash.c that aren't
covered (skew optimization, large tuples).

https://coverage.postgresql.org/src/backend/executor/nodeHash.c.gcov.html
https://coverage.postgresql.org/src/backend/executor/nodeHashjoin.c.gcov.html

- Andres

Commits

  1. Add shared tuplestores.

  2. Remove BufFile's isTemp flag.

  3. Provide DSM segment to ExecXXXInitializeWorker functions.

  4. Optimize joins when the inner relation can be proven unique.

  5. Fix failure to use clamp_row_est() for parallel joins.

  6. Document lack of validation when attaching foreign partitions.

  7. Fix inclusions of c.h from .h files.

  8. Fix inclusions of postgres_fe.h from .h files.

  9. Bring plpgsql into line with header inclusion policy.

  10. Document intentional violations of header inclusion policy.

  11. Shut down Gather's children before shutting down Gather itself.

  12. btree: Support parallel index scans.

  13. Add explicit ORDER BY to a few tests that exercise hash-join code.

  14. Revise hash join code so that we can increase the number of batches

  15. Rewrite hash join to use simple linked lists instead of a